The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems are typically used to deposit and etch thin film on substrates such as semiconductor wafers. Examples of etching include wet chemical etching and dry etching. Some dry etching is performed using plasma generated by inductively-coupled plasma. The inductively-coupled plasma may be generated by transformer-coupled plasma (TCP) coils.
Etch rate (ER) residual non-uniformity within a semiconductor wafer can be caused by non-uniformity in magnetic flux generated by the TCP coils. The non-uniformity may be caused by an increase in localized coil current due to one or more nodes forming on the TCP coil. Most inductive-coupled plasma systems including TCP coils rely on coil and chamber top end symmetry to eliminate magnetic flux non-uniformity. However, perfect symmetry is very difficult to achieve due to voltage nodes within the coil and non-symmetric surrounding hardware.